1) Make sure you're getting paid either exorbitantly well, or at least hourly 2) Ask how long it would take to write from scratch? Only ask if the answer to #1

1) Make sure you're getting paid either exorbitantly well, or at least hourly 2) Ask how long it would take to write from scratch? Only ask if the answer to #1 is "salaried well" btw. Dumping an unsupported codebase on a new employee is a major dick move, and it requires hazard pay. They are doing that because they are desperate.